Abstract:We conducted a study to investigate morphological indicators, chlorophyll, soluble sugar, ergine and ergonovine contents under different photoperiods (8, 12, 14 and 16 h·d-1) and illumination intensities (1 500, 2 500 and 3 500 lux), to explore the optimum conditions for the growth of the symbiotic Achnatherum inebrians seedling and the accumulation of alkaloids. it was found that: (1) the plant height, chlorophyll and soluble sugar content of symbiotic A. inebrians seeding were increased with the prolonging of photoperiod, which were significantly (P<0.05) lower than that of other three treatments under 16 h·d-1, but the root length, tiller amount per plant and biomass per plant were increased first and then decreaseds, which had a peak value under 14 h·d-1. (2) The plant four morphological indicators, chlorophyll and soluble sugar content of symbiotic A. inebrians seedling were increased with the illumination intensity increased that had a peak value under 3 500 lux. (3) With the prolonging of treatment time, the content of ergine and ergonovine were increased in different photoperiods. The contents of ergine and ergonovine were significantly (P<0.05) higher than that of other treatments under 12 h·d-1 and 2 500 lux, which had a peak value at 15 days. It can be seen that the appropriate light environment can significantly promote the growth of symbiont of Epichlo gansuensisAchnatherum inebrians seedling and the accumulation of alkaloids, and the most suitable condition for the accumulation of ergine and ergonovine were 12 h·d-1 and 2 500 lux.